The basics of crusher maintenance ~ primary and secondary Part I

by Colleen Suo

During the CONEXPO-CON/AGG exhibition in March 2017, the schedule of professional development sessions was full and extensive. Subjects covered ran the gamut of new product reveals to basic maintenance of a variety of equipment. During one of the maintenance sessions, KPI-JCI’s Resource Development Manager Erik Schmidt reviewed some of the basics of crusher maintenance – specifically cone and horizontal shaft impact crushers.

Although the session was almost two years ago, these basics can be applied to any crushing operation, whether you are a small mobile operator or large plant with multiple pieces of equipment.

Schmidt explained that all equipment needs maintenance, regardless of type or age of the plant – and as the plant ages, operators trade off depreciation value for repair costs. He suggested part of the operating budget should include 30 – 35 percent of the direct operating costs be designated for repairs and maintenance labor.

According to Schmidt, there are three types of maintenance approaches: preventative (PM), predictive (a.k.a. proactive) and reactive (repair-maintenance). Most companies are familiar with the term preventative maintenance but may not put it into practice. It is often viewed as unnecessary, since the equipment is running so well – but in the long run this can save expensive downtime because you are repairing before the failure, oftentimes preventing the domino effect of a multiple component failure. Predictive or proactive maintenance is somewhat similar; however, it involves analyzing the current conditions of the machines to determine when the PM service is needed before a breakdown. All machinery will wear or meet a service life expectation and need repair. Therefore, planning for the PM – whether repairs or component exchanges – will extend the useful life of the crusher.

Reactive or repair maintenance is just what the words imply. The repairs are made after the failure or breakdown – putting the job or operation in jeopardy – and usually causing a knee-jerk reaction to spend “whatever it takes” to get the equipment up and running again. This type of plan creates the highest repair costs and lowest operating availability, but unfortunately, according to assorted lifecycle management studies, up to 75 percent of companies operate under the “run her till she’s broke” mentality.

Some of the results listed from a poorly managed maintenance plan include reduced or poor equipment availability, high repair costs (both parts and labor), excessive air freight bills (overnighting a part can cost twice as much or more as standard freight), reduced income due to plant downtime and possible poor morale among employees.

Schmidt gave an example of how an inefficient maintenance program can affect your bottom line in a huge way. Based on his experience, the average plant (sand and gravel) produced 4,000 tons of product a day at (approximately) $11 a ton – that’s $44,000 in lost revenue, daily. Labor and equipment expenses for the day (in general overhead values) were estimated at $5,600, which results in a real loss of around $49,600 per day or the average plant downtime cost of $5,000 per hour.

Schmidt outlined his seven points of crusher maintenance best practices and spent a few minutes drilling down into each one. Going through the list, you can see that although each point is independent, they are integral to the whole program.

• Create a team approach to maintenance

Crews need to understand their responsibilities in the overall maintenance program and should be monitored and supported by management. Schmidt suggested challenging yourself and each other, be clear about what is expected of the team and don’t underestimate your workers’ knowledge and enthusiasm for the job. Effectively maintained equipment increases production. Incorporate some friendly competition for daily production goals. If the actual costs associated with a shutdown are understood, informed decisions can be made regarding each situation.

• Perform daily visual inspections

Visual walk-around inspections need to be performed daily, be documented and should involve all members of the team in some way. Problems and deficiencies need to be written down and analyzed to determine what appropriate steps to take to prevent a failure. Perhaps this means ordering particular parts ahead of an anticipated breakage due to wear or weakness. If certain parts tend to wear faster depending on the material being processed, be sure to keep an accurate inventory of spare parts.

• Schedule plant PM inspections

Most of the equipment on site has a suggested PM schedule from the manufacturer. Question any instructions you don’t understand regarding the scheduling – ask the OEM sales rep or your dealer. That’s what they’re there for – to make sure you get the most out the equipment.

You can also create your own maintenance recording documents if you have multiple pieces of equipment in order to coordinate the schedules more effectively. Lifecycle management software is useful for this purpose. Identify, document and reschedule PMs not performed due to operational commitments. Be sure to perform predictive maintenance tests, such as oil sampling, heat readings, vibration and sonic testing where possible.

• Schedule annual inspections

If you’ve got a regular slow season or winter shutdown, this would be the ideal time to schedule in-depth inspections, repairs and rebuilds. Use this time to be proactive. This will include component change-outs – gearboxes, hoses, belts, etc.

• Manage plant repair and work problems

Keep an accurate logbook. Schmidt emphasized this point throughout the presentation. He could not overestimate the importance of an up-to-date maintenance logbook. Problems and deficiencies should be listed for all known issues with the plant(s), with estimated repair man-hours. Parts should also be identified specifically and notated when ordered. If there are multiple plants onsite, each one should have a dedicated logbook which should be updated after each daily walk-around and after shutdown, noting any unusual occurrences the operators notice during the workday, such as temp differentials, vibratory discrepancies and the like.

• Schedule and perform daily servicing and lubrication

Know your oils and greases and be sure you know what is in your grease gun at any given point. Has the person doing the greasing really been trained properly – do they know how many pumps for what fitting? Are they sealed fittings or open? Do you know who loaded the gun last? Are the remote grease lines working well? This refers back to the daily visual walk-around inspections. Check the manufacturer’s specs for each piece of equipment. Have contamination control practices and guidelines in place, starting with pre-filtering oils and lubricants at the service unit, wiping the Zerk before pumping and no open-bucket servicing.

• Do benchmarking for the equipment

Know the normal crusher coast down times, motor amperage draw and operating temperatures. This should include bearings, oil, heat exchangers, motors and pumps. In Schmidt’s opinion, the biggest benchmark you could do is to perform an oil analysis, stating that most OEMs have a standard oil-sampling interval.

If and when you experience a failure, it was recommended to perform a root cause analysis (RCA) to determine if there is potential for recurrence or whether it was an operator or lack of maintenance-induced problem.

After reviewing his list of seven best practices, Schmidt stated that proper training is key to understanding any piece of equipment. He suggested operators take full advantage of the training programs offered by the manufacturers, whether on-site or at the OEM’s training facility. Employee training should be kept current and recorded so they are credited for their new skill set. The training should also be ongoing to stay fresh and current.

Next month we will continue with crusher maintenance best practices as reviewed by Erik Schmidt of KPI-JCI.

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